Comprehensive analysis of commercially available mouse antichicken monoclonal antibodies for cross-reactivity with peripheral blood leukocytes from commercial turkeys

In the United States, turkey production contributes approximately $14.4 billion to the US economy; however, the number of reagents specifically developed to study the immune system of this economically important species is limited. To compensate for this, laboratories focused on the turkey system have each empirically tested various chicken-specific reagents for cross-reactivity with turkeys. The result is a patchwork of reports using different genetic lines and different ages, and in many cases, leading to inconsistent conclusions about the cross-reactivity of the reagents tested. In the current study, we investigated a large panel of commercially available monoclonal antibodies specific for chicken leukocyte markers for their ability to specifically recognize the turkey homolog of their respective ligand using 2 different genetic lines of commercial turkeys. The results of these studies identify 8 chicken-specific monoclonal antibodies (F21-21, F21-2, CT4, EP96, 3-298, AV7, c264, and AV6) as demonstrating strong evidence for cross-reactivity with turkey peripheral blood mononuclear cells from both commercial lines, 3 of which (F21-2, EP96, and c264), to our knowledge, have not previously been reported. In addition, characterization of the anti-CD8α monoclonal antibody 3-298 provides evidence that turkeys, like chickens, have a relatively high percentage of CD4CD8 double-positive T-cells in circulation and have at least 5 alleles of the CD8α gene. Collectively, the results from these experiments strengthen our understanding of the turkey immune system, its relative level of conservation with the chicken system, and adds to the list of reagents that can be reliably used to assess immune responses in commercial turkeys.